Emergency workers on the ground have doubled since Thursday, with about 1,250 trying to find and rescue those still trapped, Santa Barbara County spokeswoman Amber Anderson said.

The mudslides, which came in the early morning hours of Tuesday, killed at least 18 people and destroyed dozens of homes. Those killed ranged in age from 3 to 89, and all lived in Montecito in Santa Barbara County, northwest of Los Angeles, authorities said.

Rescuers have searched frantically for the missing after rivers of mud and boulders flooded through neighborhoods in and near Montecito, an affluent seaside community east of Santa Barbara, demolishing homes and leaving roads impassable.

"In disaster circumstances, there have been many miraculous stories of people lasting many days. We certainly are searching for a miracle right now," Brown said Thursday.

"But realistically we suspect that we are going to continue to have discovery of people who were killed in this incident."

Rescue workers are using helicopters and all-terrain vehicles in a search hampered by blocked roads and downed trees and power lines.

Billy Grokenberger lives in a part of Montecito that was under a voluntary evacuation order. He and his parents put belongings in three cars in case they decided to leave before the storm. They didn't.

"We had thought about leaving, but we had just had the fires," he said, referring to the recent wildfires that stripped the area of needed vegetation. "... We didn't take it serious(ly) enough."

On the morning of the storm, Grokenberger watched as 2 to 3 feet of water streamed down the street.

"(In) four minutes the water was through our wall and in our house, almost to the second story," he said.

"The house is destroyed, but you know, there's just so many others who are less fortunate. But we just feel lucky that we were able to get out and (are) alive."

Risk of mudslides for years

The storm hit hard between 3 and 6 a.m. Tuesday. The rain poured down on hillsides charred by recent wildfires, which burned vegetation that otherwise could make the terrain more resistant to mudslides.

Short term, making the public ready to evacuate during heavy rains is key, he said.

Montecito and Carpinteria are especially vulnerable to mudslides because the steep terrain in some places goes from thousands of feet above sea level to sea level in just a few miles, said Tom Fayram, a deputy public works director with Santa Barbara County.